As the whisker bends, the distance between the nanoparticles changes and this in turn changes the electrical resistance of the whisker.

The carbon nanotubes help maintain electrical flow when the silver nanoparticles are very far apart and can increase the range of pressure the whisker can sense, says Takei.

"If we have carbon nanotubes, we can increase the dynamic range of the sensing."

The amount of pressure, and the direction it is coming from, can be detected, using a processor connected to the whisker.

Sensitivity

In their lab tests the researchers found the whiskers were able to pick up the direction and force of flow of a wind that was blown past the whiskers - with a pressure as low as 1 Pa with high sensitivity.

This suggests these new whiskers could be useful for enhancing the sensitivity of artificial skin.

"Usually our skin can detect very low pressures. Hair on the skin can help to detect wind flow," says Takei. "Current artificial skin can't detect very low pressures like wind."

For use in robot navigation, the electronic whiskers would need to be "tuned" so they are less sensitive and don't pick up the vibrations caused simply by the movement of the robot.

"If the sensors are too sensitive they will pick up the robot's vibrations and that will not be good," says Takei.

"By changing the ratio of the carbon nanotubes and silver nanoparticles we can change the sensitivity and resistivity of the sensors," says Takei.